The action parameter

NRAO Home > CASA > CASA Cookbook and User Reference Manual

3.4.1 The action parameter

The keyword action controls whether the actual flagging commands will be applied or not and the options are the empty string ’’, ’apply’ and ’calculate’.

apply is likely the most popular one as it applies the flags to the MS:

action              =    ’apply’        #  Action to perform in MS and/or in inpfile
                                        #   (none/apply/calculate)
     display        =         ’’        #  Display data and/or end-of-MS reports at runtime
                                        #   (data/report/both).
     flagbackup     =       True        #  Back up the state of flags before the run

flagbackup specifies if a backup of the current flags should be saved in the ‘‘*.flagversions’’ file. display can be ’’, ’data’, ’report’, ’both’ where the empty string ’’ will report no individual flagging statistics, whereas ’data’ launches an interactive GUI to display data and flags for each chunk to browse through. The plots are time-frequency planes and both old and new flags are being overlaid for all correlations per baseline. In the GUI, one can step though all chunks for inspection and if the flagging is unsatisfactory, one can exit without applying the flags. If the flagging is acceptable, it is also possible to continue flagging without viewing all chunks (the number of chunks can be very large for typical JVLA and ALMA data sets. display=’report’ lists the flagging statistics at the end of the procedure on the screen and both starts the GUI and reports all statistics at the end.

action=’calculate’ calculates the flags but does not write them to the MS. This is useful if one would like to inspect the computed flags in the GUI without a straight application:

action              = ’calculate’       #  Action to perform in MS and/or in inpfile
                                        #   (none/apply/calculate)
     display        =         ’’        #  Display data and/or end-of-MS reports at runtime
                                        #   (data/report/both).

The empty string action=’’ will do nothing and is useful when the commands themselves shall only be written to the FLAG_CMD sub-table or to an external file using the savepars parameter to specify the filename.

savepars will save the flagging commands to a file that can be later used for input in flagdata via mode=’list’. It also shares the flagcmd syntax and can be used there. The file name is specified by outfile and, if empty, the FLAG_CMD table in the MS will be populated. A REASON can be given by the reason keyword which may be useful for bookkeeping as well as for unflagging data that are marked by specific REASON keywords.

[next] [prev] [prev-tail] [front] [up]

More information about CASA may be found at the CASA web page

This code is available under the terms of the GNU General Public Lincense